If Ball ever came to Boston it would only be to sit on the bench for the next 2 years and then be traded on for another asset.
So yeah, the Celtics aren't really drafting Ball. Not unless it's a pre-arranged draft day deal, where Celtics pick Ball for the Lakers or another team and then immediately trade him.
Ball only really makes sense for the Lakers or the Suns. 76ers already have Simmons so I doubt they are trying to move up for Ball when they can just sit and take De'Aaron Fox at #3.